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Role of Singlet and Triplet Excitons in Extrinsic Photocurrent Production in the Anthracene–Gold System
Author(s) -
Chance R. R.,
Prock A.
Publication year - 1973
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220570217
Subject(s) - exciton , anthracene , singlet state , chemistry , singlet fission , photocurrent , excitation , molecular physics , photochemistry , atomic physics , materials science , condensed matter physics , optoelectronics , physics , excited state , quantum mechanics
Extrinsic hole photocurrents in a gold coated anthracene crystal are measured as a function of the absorption depth of the exciting light. Charge pairs are formed at the gold‐anthracene interface as a result of exciton–gold interactions. It is found that both singlet and triplet excitons are involved as precursors to charge formation. The contributions of singlets and triplets to the observed photocurrent quantum yields are determined for 394 nm excitation light ( a and b polarized) and 340 nm excitation light ( a and b polarized). Since reabsorption is known to have a significant effect on the distribution of excitons and on the effective singlet lifetime, a steady state numerical solution for the reabsorption problem is offered for this system. The inclusion of the reabsorption effect allows the calculation of a “reabsorption free” singlet diffusion length (316 Å) and an evaluation of the electron transfer efficiency ratio (η T /η S ≈ 3.5) where η S is the probability of electron injection per singlet exciton quenched by the surface and η T is the corresponding probability for a triplet exciton. The magnitude of the ratio η T /η S is interpreted in terms of singlet energy transfer to the gold layer.